System for communication enhancement in a noisy environment

Abstract

The invention is directed to a method comprising receiving input signals emanating from at least two microphone arrays each comprising at least two microphones, processing the input signals of each microphone array by a beamformer to determine temporal and spatial information about the input signals of each microphone array.

1. A method for enhancing communication in a noisy environment comprising:
 receiving input signals emanating from at least two microphone arrays each comprising at least two microphones; and 
 processing the input signals of each microphone array by an adaptive wanted signal beamformer and a blocking beamformer, the processing comprising:
 determining temporal and spatial information about the input signals of each microphone array; 
 obtaining a wanted signal from the adaptive wanted signal beamformer; 
 obtaining a blocking signal from the blocking beamformer; and 
 deciding whether a signal is transmitted from a wanted signal direction, the deciding comprising:
 determining a wanted signal power; and 
 determining a blocking signal power, 
 wherein the adaptive wanted signal beamformer is adapted only if no signal is transmitted from the wanted signal direction, which is determined as when the blocking signal power is larger than a predetermined constant times the wanted signal power. 
 
 
 
     
     
       2. The method of  claim 1 , further comprising detecting speech activity for each microphone array. 
     
     
       3. The method of  claim 2 , wherein detecting speech activity for a microphone array comprises:
 determining a wanted signal power, a blocking signal power, and a background noise signal power, comparing the wanted signal power with the blocking signal power and the background noise signal power. 
 
     
     
       4. The method of  claim 3 , further comprising comparing the wanted signal powers of at least two microphone arrays and determining a highest power. 
     
     
       5. The method of  claim 2 , further comprising applying an attenuation to the processed input signals of a microphone array if no speech activity is detected for the microphone array. 
     
     
       6. The method of  claim 5 , wherein applying the attenuation is performed adaptively, preferably by varying the attenuation in predetermined time steps between zero attenuation and a predetermined maximum attenuation. 
     
     
       7. The method of  claim 1 , wherein processing comprises determining a gain control of the input signals for each microphone array. 
     
     
       8. The method of  claim 7 , wherein determining a gain control is performed adaptively. 
     
     
       9. The method of  claim 1 , further comprising selecting at least one output channel out of at least two output channels on which the processed signals are to be output. 
     
     
       10. The method of  claim 9 , wherein selecting the at least one output channel comprises determining an amplification for each selected output channel. 
     
     
       11. A communication system comprising:
 at least two microphone arrays each comprising at least two microphones to produce microphone signals; 
 at least one analog/digital converter having an input for receiving said microphone signals and an output for providing digital microphone signals; 
 a digital signal processor having an input for receiving the digital microphone signals, the digital signal processor configured to:
 process the digital microphone signals of each microphone array by an adaptive wanted signal beamformer and a blocking beamformer, the processing comprising:
 determining temporal and spatial information about the microphone signals of each microphone array; 
 obtaining a wanted signal from the adaptive wanted signal beamformer; 
 obtaining a blocking signal from the blocking beamformer; and 
 deciding whether a signal is transmitted from a wanted signal direction, the deciding comprising:
 determining a wanted signal power; and 
 determining a blocking signal power, 
 wherein the adaptive wanted signal beamformer is adapted only if no signal is transmitted from the wanted signal direction, which is determined as when the blocking signal power is larger than a predetermined constant times the wanted signal power; and 
 
 
 provide processed output signals to at least two loudspeakers. 
 
 
     
     
       12. The communication system of  claim 11 , wherein the digital signal processor is further configured to select at least one loudspeaker out of the at least two loudspeakers on which the processed signals are to be output. 
     
     
       13. A vehicular cabin comprising a communication system according to  claim 11  and at least two loudspeakers, wherein each microphone array and each loudspeaker is associated with a passenger seat.